A mobile communication system has been developed to provide audio services while assuring activities of users. However, the mobile communication system has been extended its coverage to data service as well as audio service, and has been currently developed to provide data services of high speed. More advanced mobile communication system has been required due to a lack of resources in the mobile communication system, which currently provides services, and a request of services of high speed from users.
One of important things in requirements of a next generation wireless access system should support a demand of a high data transmission rate. To this end, various technologies such as multiple input multiple output (MIMO), cooperative multiple point transmission (CoMP), and relay have been studied. In order to allow a radio data request, which has been rapidly increased, application of heterogeneous networks of a macro-pico or macro-femto has been increased.
However, a pico cell or a femto cell in the heterogeneous network environment is located within a macro cell. Under the circumstances, a problem occurs in that signals transmitted from the respective cells to a user equipment located at the boundary of cells which are overlapped with each other act as mutual interference.